FD sets reference documentation could be much improved

Hi,

The reference documentation for FD sets could be much better.  It's very
minimalist, leaving the reader to guess some of the details.  Sometimes the
relevant details can be gleaned from the user manual, but other times not.
There also doesn't seem to be any mention anywhere (user manual or reference
manual) that set elements can only be positive.

Examples:

    membership_booleans(?Set, ?BoolArr)

    BoolArr is an array of booleans describing Set 

    Set 
	A free variable, set variable or an integer list 
    BoolArr 
	A variable or an array (structure) of boolean variables 

    What is the relationship between the array and the set?  Presumably the
    boolean in position i corresponds to whether or not the integer i is in
    the set, but this is not specified.  Is it defined what the size of the
    array is?  E.g. does it correspond to the largest integer of the initial
    upper bound, or is it undefined?  Are the booleans updated when the set
    is?  Can the set be updated by modifying the booleans?  Etc.


    #(?Set, ?Card)

    Card is the cardinality of the integer set Set 

    It is not specified that Card is an FD variable, nor that it is
    "updated" when the set is modified and can be used to impose extra
    constraints on the cardinality of the set.  (I.e. it's not just looking
    up the current state.)


    ?Set :: ++Lwb..++Upb

    Set is an integer set within the given bounds

    What constitutes legal bounds?


Cheers,
Warwick